Rape by deception is actually a law.
But I belive its more for things like agreeing to wear a condom then sneaking it off etc.
I know claiming to be a millionaire etc is not covered by it.
The 'deception' for a rape (or other sexual offence) has to be relevant to the nature of the 'act' itself not the general status of the parties involved ...
Examples....
Naive female has sex with a man who says it will improve her singing voice - offence commited as the 'act' has been misrepresented
Trans female to male individual (pre op) has sex with a (biological) woman penetrating her with a prosthetic penis whilst purporting to be a (biological) man using an actual penis - offence conmitt as the 'act' has been misrepresented.
Man doesn't use condom after permission given for sexual intercourse on the express condition that he did wear one - offence committed as the 'act' is misrepresented....
Man claims to be a millionaire, football player, astronaut, not a police officer etc to have sex with another person - not an offence as the 'act' has not been misrepresented....
If you changed this in law then you would open up adulterers (who don't tell their respective partners about the other) and woman lying about birth control to prosecution....
You can also be prosecuted if you mis represent who you are
for a specific person the victim would consent to sexual activity with .... I. E
An identical twin gets into bed with his brothers partner and has sex pretending to be the partner - offence commited
Or man slips into mates bed with mates wife in the dark and pretends to be mate to have sex with mates wife - offence commited.